This proposal is aimed at understanding the role of the HTLV LOR production in transcriptional activation of specific target sequences, and how this process relates to the transforming ability of the virus. We wish to characterize the HTLV LOR product for subcellular location and DNA binding properties and to express it in prokaryotic and eukaryotic vector systems. We are specifically interested in expressing the LOR product in the absence of other HTLV related proteins to clearly define its role in trans-activation of the HTLV LTR and of particular cellular genes, as well as in the ability of HTLV to immortalize primary lymphocytes.